A Russian plane has conducted a surveillance flight over the U.S. Capitol building, Central Intelligence Agency, Pentagon, and other critical government centers in Washington after being cleared by the Pentagon.

The August 9 flight, which created a stir in U.S. media and political circles, was part of a long-standing program of surveillance under the Open Skies Treaty that allows both countries to fly unarmed observation planes over each other's territory.

Besides Russia and the United States, 32 other states have signed the treaty, which is aimed at fostering transparency about military activity, reducing mistrust and misunderstandings, and facilitating the monitoring of arms-control agreements.

CNN and Politico reported that besides buzzing over Washington, the Russian Tu-154M plane is due to fly over Bedminster, New Jersey, where President Donald Trump is vacationing, and the presidential retreat in Camp David, Maryland.

Pentagon spokesman Dan Gaffney said he could not confirm the path of the plane until its mission was over. "A typical mission has several segments taking place over a few days," he said.

But the U.S. Capitol Police issued an advisory ahead of time, saying an "authorized low-altitude aircraft" would enter restricted airspace over the Capitol between 11 a.m. and 3 p.m. on August 9.

"The aircraft will be large and may fly directly over the U.S. Capitol," the police notice said. "This flight will be monitored by the U.S. Capitol Police command center and other federal government agencies."

Since the treaty entered into force in 2002, there have been more than 1,200 Open Skies flights. According to the Pentagon, the overflights are conducted by aircraft typically equipped with film and sensors allowed under the treaty.

The Pentagon and State Department said that before the flights, each state is given the flight plan of the mission and escorts fly aboard the aircraft to make sure it complies with the treaty. After each flight, the host country gets a copy of any imagery taken by the observation aircraft.

U.S. officials have testified in the past that while Russia complies with the Open Skies Treaty, they believe it has adopted measures that are inconsistent with the spirit of the accord.

The treaty, for instance, obligates each member to make all of its territory available for observation, yet officials said Russia has imposed restrictions on surveillance over Moscow and Chechnya and near Abkhazia and South Ossetia, two breakaway regions of Georgia now under Russian control.